Double-penetration reduced-range hunting bullet

ABSTRACT

PCT No. PCT/FR95/01170 Sec. 371 Date Jun. 27, 1996 Sec. 102(e) Date Jun. 27, 1996 PCT Filed Sep. 13, 1995 PCT Pub. No. WO96/08689 PCT Pub. Date Mar. 21, 1996The invention relates to munitions for weapons of small, medium or large caliber. The munitions include a subprojectile combined with a launcher which fills the bore of the weapon and which detaches under the effect of the aerodynamic forces on leaving the weapon, the assembly being incorporated into a cartridge which furthermore comprises a primed case and a propellent charge. The subprojectile includes a body made of hard material, combined with an axisymmetric element including a front central nozzle communicating with at least two annular nozzles to channel the airflow.

The present invention relates to munitions for weapons of small, mediumand large caliber, and more particularly to a new double-penetrationreduced-range bullet of the type including a subprojectile combined witha launcher, actuated by a propellent system.

BACKGROUND OF THE INVENTION

Munitions of the flechette type are known in the sporting and militaryfields and, for example, Patent FR-A-2,335,818 describes a huntingmunition which includes a fin-stabilized subcaliber projectile combinedwith a launcher sabot. The latter is made of a material likely tofragment on leaving the barrel of the weapon, and dispersion of thefragments then represents a risk to the user's safety.

Patent FR-A-2,555,728 describes a munition of the same type, that is tosay one which includes a fin-stabilized subprojectile associated with adetachable launcher which has the effect of guiding and sealing it as ittravels along the barrel of the weapon. The subprojectile has a taperedshape and is made of a high-density material giving it a high surfaceenergy on impact. However, this characteristic has the drawback of oftencausing only slight wounding of the game animal, it being possible infact for the subprojectile to pass through the soft flesh of the gameanimal without encountering a hard part. Furthermore, the projectile maybe driven a long distance if the target is missed, because of its goodtrajectory stability, and it may then constitute a danger for people inthe vicinity.

Patent FR-A-2,627,854 relates to a hunting munition which includes aprojectile consisting of an internal element, the front and side wallsof which are covered with an external element in the form of a sleeve.The metal internal element includes a head having a neutralizing shape,fastened to a rear rod on which a hammer mass may slide in order toincrease the neutralizing effect of the projectile upon impact. However,the external element remains fixed to the internal element over theentire trajectory of the projectile; it cannot be assimilated into alauncher such as used in flechette bullets and cannot afford the sameadvantages.

In addition, projectiles of this type have the drawback of exhibitinghigh aerodynamic drag and sensitivity to transverse wind. They also havea certain propensity to ricochets on obstacles such as tree trunks.

SUMMARY OF THE INVENTION

The subject of the present invention is a munition of the flechettetype, including a subprojectile combined with a launcher which fills thebore of the weapon and which detaches under the effect of theaerodynamic forces on leaving the barrel of the weapon. The assemblyconsisting of the subprojectile (or bare bullet) and the launcher areincorporated into a cartridge which furthermore comprises a primed caseand a propellent charge. This munition possesses characteristicsenabling it to avoid the drawbacks of the aforementioned knownprojectiles and it may be used especially in hunting weapons as well asmilitary training weapons.

According to one characteristic of the invention, the subprojectilecomprises:

a body made of hard material combined with

an axisymmetric high-energy element which includes a front centralnozzle communicating with at least two annular nozzles channeling theairflow.

In accordance with the present invention, the high-energy element formsthe front part of the subprojectile and it preferably consists of ahollow outer element and a solid inner element which are connectedtogether by blades, the inner element preferably having a smallerdiameter and lying to the rear of the outer element.

According to a preferred embodiment, the high-energy outer element formswith the conical head of the subprojectile body a central nozzlecommunicating with the annular nozzles, formed in the axisymmetrichigh-energy element, around the conical head.

The high-energy element may be made in accordance with the invention insuch a way that the outside diameter of its outer element substantiallyfills the bore of the weapon. In this embodiment, the launcher is placedon the subprojectile, to the rear of the outer high-energy element.According to one variant, the outer high-energy element may itself besubcaliber, but its outside diameter remains greater than that of thebody of the subprojectile. In this embodiment variant, the shape of thelauncher is designed to cover the subprojectile entirely, that is to saythe body and the axisymmetric high-energy element.

The inside diameter of the nozzle-shaped outer high-energy element maybe greater than, equal to or less than the outside diameter of the innerhigh-energy element.

The axisymmetric high-energy element may be separable from the body onwhich it is mounted but, in a variant, the body and the high-energyelement may be made as a single homogeneous piece in the same material.

In addition, the high-energy element may be made so as to befragmentable upon impact on the target. This effect may be obtained byusing a material having an appropriate impact strength, and in this casethe body of the subprojectile and the high-energy element are made oftwo different materials and are joined together during manufacture. Forexample, provision may be made for the axisymmetric high-energy elementto be made of a material having a lower impact strength than the body ofthe subprojectile made of a hard material. It is also possible toprovide fracture initiators in the high-energy element, for example inthe region of the connection between the outer element and the innerelement, and preferably the base of the blades separating the annularnozzles or in the thickness of the central nozzle. In this embodiment,the body of the subprojectile and the axisymmetric high-energy elementmay be manufactured as one and the same piece.

Moreover, it is advantageous in accordance with the invention for thefront face of the axisymmetric high-energy element to have an insidechamfer. According to another advantageous embodiment, the internalsurface of the axisymmetric high-energy element possesses afrustoconical shape in which the inside diameter of its front part isslightly greater than the inside diameter of its rear part.

A complete round (projectile) in accordance with the invention iscomposed of the two essential elements consisting of the bare bullet(subprojectile) and the launcher.

The launcher may be made according to known techniques and it may bemade as a single monobloc or as a plurality of longitudinally contiguouselements. It may also be divided into at least two transversely separatemonobloc elements. In accordance with the invention, it may beadvantageous for the launcher to include a rear face having a cutout ofshape corresponding to the fin assembly of the subprojectile.

A seal may be provided between the body of the bullet (subprojectile)and the launcher and, preferably, an annular seal is installed on athrust plate located between the head and the fin assembly of the bodyof the bullet so as to ensure sealing with respect to the propellentgases after the charge has been fired.

The sealing between the launcher and the barrel of the weapon may beachieved, in accordance with the invention, by means of an annular lipformed on the periphery of the rear face of the launcher, or of at leastone element of the launcher, in such a way that this annular lip ispressed against the wall of the barrel by the pressure of the gasesafter the charge has been fired.

The munition in accordance with the present invention has manyadvantages compared with the known munitions in the same field ofapplication. More particularly, it permits:

generation of wounds in the soft parts of the game animal byfragmentation of the high-energy element in quite a wide fragmentationcone;

rapid penetration of the flechette, consisting of the body and the innerhigh-energy element, in order to attack the hard parts of the gameanimal's skeleton and to create a large shock wave;

a reduced range of the bullet, the reduction in range beingpredetermined and possibly associated with destabilization of the saidbullet. This result may be obtained in a known manner by an internalaerodynamic effect;

rapid separation of the launcher, also based on an internal aerodynamiceffect;

a monobloc launcher to remain in the plane of firing after it hasseparated from the bullet;

low propensity of the bullet to ricochets;

improved ballistic dispersion;

reduction in the mass of lead involved;

firing in all full-choke smooth-bore, slightly rifled and highly rifledweapons;

use of the same bullet for various calibers (for example 12, 16, 20,etc. calibers).

Tests carried out with bullets made in accordance with the presentinvention, compared with known bullets, have demonstrated the excellentresults afforded by the invention.

In fact, when the trajectory of a no-nozzle bullet (range a) is comparedwith that of a bullet with only aerodynamic braking, which bullet isfired under the same conditions (range b), and with that of a bullet inaccordance with the invention, with braking by aerodynamic blocking anddestabilization over the trajectory (range c), the relationship c<b<a isobserved, that is to say that the range is markedly limited in the caseof the invention.

The advantage afforded by a braking and destabilization which areassociated with the reduced range is particularly useful in the case ofpractice munitions, while the double penetration of the high-energyelement and of the flechette constitutes a major advantage in the caseof hunting munitions. Furthermore, the kinetic energy per unit area ofthese two elements are very high, in accordance with the invention, asindicated hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics and advantages of the invention will appear moreclearly on reading the following description, with reference to theappended drawings, relating to preferred embodiments, which represent:

FIG. 1: a diagrammatic section through a complete cartridge inaccordance with the present invention, comprising a complete round,consisting of a bare bullet and a launcher, and a primed case as well asa propellent charge.

FIG. 2: a longitudinal section through the bare bullet of FIG. 1.

FIG. 3: a front view of a simple variant of the bare bullet of FIG. 2.

FIG. 4: a section through the launcher combined with the bare bulletshown in FIG. 1.

FIGS. 5-8: embodiment variants in accordance with the present invention.

These illustrative embodiments all refer to hunting or small-calibermunitions, but it, is clear that the invention may be adapted topractice munitions without departing from the scope of the presentdescription.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, the cartridge (C) comprises the bare bullet (2), thelauncher (3) as well as the primed case (D) containing a propellentcharge, consisting here of a powder (P) of conventional type.

The bare bullet (2), shown in more detail in FIG. 2, includesessentially two elements:

the body (4), made of hard material (for example brass), which includesa conical head (5), a core (7), a thrust plate (11) and a fin assembly(18) serving to stabilize the projectile over its trajectory;

an axisymmetric high-energy element (25) consisting of an inner element(10) and an outer element (26) which are connected together by blades(27), thus forming annular nozzles (6) around the conical head (5), theinner element (10), of smaller diameter, being set back to the rear ofthe outer element (26).

The shape of the annular nozzles (6) delimited by the blades (27) isseen more clearly in FIG. 3, showing a bare bullet having an outerelement (26) of cylindrical shape and four annular nozzles.

The conical head (5) of the body (4) of the bare bullet (2) is designedin accordance with the present invention to provide several functions,and more particularly to promote airflow through the annular nozzles(6), to permit good catching of the bullet on the targets encounteredand to penetrate into the matter with a very high neutralizing power.

The core (7) is provided with keys (8) interacting with the circulargrooves (9) in the inner high-energy element (10).

The thrust plate (11) ensures

a--integrity of the inner high-energy element (10) at the interface (12)during the phase of propulsion of the bare bullet (3) as well as duringthe phase of penetration into the target;

b--sealing with respect to the propellent gases between the launcher (3)and the body (4) by virtue of the seal (13) made of deformable materialinteracting with the groove (14);

c--guiding of the launcher (3) by its cylindrical outer part (15);

d--thrusting of the central part of the bare bullet (2) body (4)+innerhigh-energy element (10)! by virtue of the interaction of the rear partof the launcher (3) and of the rear face (16) which itself includes ashoulder (17) so as to permit better guiding of the launcher (3).

The fin assembly (18) serves to stabilize the bare bullet (2) over itstrajectory. It is made either in the same material as the body (4), thatis to say preferably brass, or in a material of the engineering-polymertype.

The fin assembly conventionally consists of and is composed of:

a--fins (19), the number and shape of which are related to the flightconditions of the bare bullet (2), according to a standard technique. Ingeneral, it is preferable for the fin assembly to have four fins. Eachfin includes a trailing edge chamfer (20) to permit the bare bullet (2)to rotate slightly over its trajectory. The front (21) of the fins (19)may fit into corresponding grooves made in the launcher (3), thusallowing angular locking of the bare bullet (2) with the launcher (3).The outside diameter (a) of the fins (19) is preferably slightly lessthan the outside diameter (b) of the inner high-energy element (10)which itself is equal to the outside diameter of the thrust plate (11);

b--a fin-assembly body (23) also serving to guide the launcher (3) atthe interface (24).

The high-energy element (25) is made of a dense material, for examplelead, but any other high-density metallic material may be suitable, forexample a metal alloy of appropriate density or alternatively anorganic/metallic hybrid alloy.

The two elements (10) and (26) of the high-energy element (25) areconnected together by the blades (27), the number of which depends onthe flight characteristics, on the mechanical integrity of the completeround (1) during the propulsion phase as well as on the behavior of thebare bullet (2) upon penetrating the target. The number of bladesgenerally lies between 2 and 8 and is preferably equal to 4. In theirouter part, these blades have a step (28) interacting with the internalpart (29) of the launcher (3), the latter thus being guided in its frontpart.

On its outer part, the outer high-energy element (26) includes circularparts (30) as well as slots (31). In order to avoid coating the barrelof the weapon with lead, it is preferable for the circular parts (30) tohave a diameter (c) less than or at most equal to the outside diameterof the launcher (3), for the number and width of the said bearingsurfaces to be as small as possible and for the slots (31) to have adiameter (d) less than the exit diameter of a "full choke" barrel of theweapon.

The front face (32) of the outer element (26) has as small as possiblean area. The latter is influenced by the magnitude of the inside chamfer(33) whose other function is to promote, on the one hand, thepenetration of air into the central nozzle (34) and, on the other hand,fragmentation over a wide cone at the start of penetration of the barebullet (2) into the target by shattering of the element (26).

The rear face (35) of the outer element (26) mates with the front face(36) of the launcher (3) in order to ensure mechanical integrity of theouter high-energy element (26) during the phase of propulsion of thecomplete round (1). The inner part (37) of the outer element (26)delimits the central nozzle (34) of cylindro-conical shape whichinteracts with the annular nozzles (6) the number of which is equal tothe number of blades (27). The inside diameter (e) of the rear part ofthe central nozzle (34) can be either greater than, less than or equalto the outside diameter (b) of the inner high-energy element (10) and ofthat of the thrust plate (11). Of course, this central nozzle (34) mayhave a simply cylindrical shape of constant inside diameter from thefront to the rear.

In order to improve the fragmentation of the outer high-energy element(26), longitudinal fracture initiators, the numbers and shapes of whichare different, may be made in the thickness of the cylindrical wall ofthe element.

The shape of the annular nozzles (6) has curvi-linear contours. Theprecise dimensioning of the nozzles (34) and (6) is determined by theusual methods in the art, depending on the flight characteristics whichit is desired to obtain, on the penetration characteristics in thetarget as well as on the mechanical integrity of the high-energy element(25) during the phase of launching of the complete round.

The nozzles may have any geometrical shape, for example a square,triangular, round, oblong or conical shape.

The inner high-energy element (10) has an outside diameter (b) less thanor at most equal to the inside diameter (e) of the rear part of thecentral nozzle (34). Over its inside face, it has circular grooves (9)interacting with the keys (8) of the core (7). Its front face (38)comprises a conical part (39) forming the inside part of the annularnozzles (6) so as to be continuous with the conical head (5) of the body(4) of the bare bullet (2). Its rear face mates with the front face ofthe thrust plate (11) at the interface (12).

The body (4) combined with the inner high-energy element (10) makes upthe flechette (40) of the bare bullet (2). The flechette (40) isdirected over its entire trajectory right up to the target by the outerhigh-energy element (26).

The launcher (3), shown in FIG. 4, is manufactured from a materialhaving a low density and a high flexibility (for example an engineeringpolymer such as a polyamide). The launcher (3) is monobloc and can slidefreely until it comes in contact with the outer element (26), the stepof the blade (27) and the thrust plate (11). On its outside part, it hasnarrow keys (41) permitting the complete round (1) to be guided in thebarrel of the weapon. Decompression slots (42) provide good sealing withrespect to the propellent gases, which sealing is also provided to alarge part by the lip (43) by pressing of this latter element againstthe wall of the barrel of the weapon under the effect of the pressure.This arrangement permits firing in all full-choke barrels, withoutdegradation of the ballistic dispersion of the bare bullet (2), and alsoincreases the lifetime of the weapons.

The front face (36) of the launcher (3) interacts with the rear face(35) of the outer high-energy element (26) in order essentially toensure mechanical integrity of the element (26) during the phase ofpropulsion of the complete round (1).

On its front part, the inside part of the launcher (3) comprises a step(29) mating with the corresponding step (28) of the blades (27) and thuspermitting front guiding of the launcher (3). This launcher (3) has abore (44) whose inside diameter (f) is greater than that (b) of theinner high-energy element (10) (a few tenths of a millimeter clearance)and a bore (45) interacting with the outside part (15) of the thrustplate (11), thereby making it possible partly to ensure rear guiding ofthe launcher (3). In addition, the step (46) interacts with the rearface (16) and the shoulder (17) of the thrust plate (11), thus making itpossible also partly to ensure rear guiding of the launcher (3) andmechanical integrity of the assembly during the propulsion phase.

The bores (44) and (45) are connected by the conical part (62). The bore(47) interacts with the fin-assembly body (23) and thus makes itpossible to improve the rear guiding of the launcher (3). The grooves(22), the number of which is equal to the number of fins (19) of the finassembly (18), ensure, by interaction with the front part (21) of thefins (19), angular locking of the bare bullet (2) with the launcher (3),the diameter (g) of the bottom of the grooves being slightly greaterthan the outside diameter (a) of the fins (19).

The operation of the munition in accordance with the present inventionis described hereinbelow.

At the start of firing and during the pressure rise, the unfastening ofthe case takes place by means of the outer high-energy element (26).During the phase of propulsion of the complete round (1), the barebullet (2) and the launcher (3) are intimately linked. Immediately onleaving the barrel of the weapon, the launcher (3) slides on the barebullet (2) due to the difference in frictional aerodynamic drag on thebare bullet (2) and on the launcher (3) and to the air pressure which isgenerated in the central nozzle (34) and in the annular nozzles (6) andwhich is exerted essentially on the step (29) of the launcher.

The bare bullet (2)/launcher (3) sliding zones have differentdimensions, the final point of contact having to take place in front ofthe center of gravity of the bare bullet (2) and as close as possible tothis center of gravity. This arrangement makes it possible partly tocompensate for the small perturbations associated with the launcher(3)/bare bullet (2) separation.

The monobloc launcher (3) thus released remains in the plane of firinguntil it falls to ground, this occurring at an average distance of from30 to 40 meters from the firer. It thus makes firing completely safe,for example, with respect to other hunters.

Over the trajectory, the bare bullet (2) is stabilized by the finassembly (18) of the flechette (40), this latter element also fulfillingthe role of fin assembly for the outer high-energy element (26).

The central nozzle (34) and the annular nozzles (6) may be dimensionedso as to create aerodynamic blocking or unblocking. Aerodynamicunblocking occurs when, for a given velocity V₁, the air flows from thecentral nozzle (34) to the outside by passing through the annularnozzles (6) under the sole condition that this velocity V₁ be greaterthan the so-called "critical" velocity V_(c). Aerodynamic blockingoccurs at a velocity V₂, less than the velocity V₁. In this case, aircan no longer flow through the nozzles. This aerodynamic blocking ischaracterized by a large increase in the aerodynamic drag which may beup to a factor of 2, thus leading to a shorter range for the bare bullet(2). Moreover, this aerodynamic blocking causes shifting of the centerof the aerodynamic forces applied to the bare bullet (2) toward thecenter of gravity of the said bullet. Decreasing this distance may leadto complete destabilization of the bullet at a given distance. Thisphenomenon, associated with a high aerodynamic drag, permits very shortranges to be obtained.

The attack mechanism is executed in two phases:

In a 1st phase, the outer high-energy element (26) strikes firstly thetarget by means of its front face (32) with the total energy of the barebullet (2).

At this precise moment, three phenomena occur chronologically:

a--a first neutralizing effect due to the very high kinetic energy perunit area (1/2 m·V² : annular cross section of the outer high-energyelement (26)) thus permitting generation of a large shock wave withdilaceration.

b--a second neutralizing effect by fragmentation of the outerhigh-energy element (26) over a wide fragmentation cone.

c--release of the flechette (40). This latter element, which issignificantly subcaliber compared to the outer high-energy element (26),is not perturbed by the fragmentation of the said element.

In a 2nd phase, the flechette (40), the release of which has absorbedvirtually no energy, thus strikes the target with the total energy ofthe bare bullet (2). As the target has become less hard because of thework produced by the outer high-energy element (26) during the 1stphase, the flechette (40) may easily enter the target with its totalenergy. Due partly to the inner high-energy element (10), theneutralizing power, from dilaceration, inhibition and fracture of hardparts, is exceptional. It should be noted that, at the moment ofpenetration into the target, the kinetic energy per unit area of theflechette (40) (1/2 m·V² : maximum cross section of the body of theflechette) is exceptionally high.

This two-phase attack mechanism makes it possible to obtain very highkinetic energy per unit area of the outer high-energy element (26) andof the flechette (40). The present invention furthermore permits veryeasy control of the value of the kinetic energy per unit area to beimposed on the outer high-energy (26) and on the flechette (40).

Several examples of munitions in accordance with the invention, producedby conventional manufacturing techniques, are described hereinbelow.

EXAMPLE 1

Characteristics of a 12-caliber bullet:

    ______________________________________                                        Total mass of the complete round                                                                    M.sub.t = 30.0 g                                        Mass of the launcher (3)                                                                            M.sub.L = 4.5 g                                         Total mass of the bare bullet (2)                                                                   M.sub.b = 25.5 g                                        Mass of the high-energy element (25)                                                                M.sub.p = 18.5 g                                        Mass of the bullet body (4)                                                                         M.sub.c = 7.0 g                                         V.sub.o = 500 m/S  sic!                                                       Energies of the bare bullet (2) at the                                        mouth of the barrel:                                                          Kinetic energy:       E.sub.k = 3200 J                                        Kinetic energy per unit area of the                                                                 Ek/ .S.sub.1 = 32 J/mm.sup.2                            outer high-energy element (26):                                               Kinetic energy per unit area of the                                                                 Ek/ .S.sub.2 = 33 J/mm.sup.2.                           flechette (40)                                                                ______________________________________                                    

In this embodiment, virtually identical Ek/.S values may be observed.

Several technological variants of the bullet in accordance with thepresent invention were manufactured and are specified hereinbelow. Ofcourse, various modifications may be made to them without departing fromthe scope of the present invention.

EXAMPLE 2

This example describes a launcher made from a plurality of contiguouselements.

The bare bullet (2) may be fired with a launcher composed of a pluralityof elements having contiguous planes, as is shown in FIG. 5.

FIG. 5 describes a complete round provided with such a launcher composedof two elements (49). These latter elements interact with the barebullet (2) by means of circular grooves (50) and of keys.

As shown in FIG. 6, under the effect of the aerodynamic components, theelements (49) of the launcher detach from the bare bullet (2) which,released, reaches the target. The elements (49) drop at an averagedistance of 30 meters, with a maximum deviation of 7 meters with respectto the plane of firing.

EXAMPLE 3

As shown in FIG. 7, the launcher (3) according to the invention ismounted on the bare bullet (2), the outer high-energy element (26) ofwhich has an outside diameter appreciably smaller than the outsidediameter of the launcher (3) and an inside diameter substantially equalto the diameter of the body of the flechette (40) (diameter c<outsidediameter of the launcher and diameter e=diameter b).

In this configuration, the launcher (3) includes centering (48) whichmates with the outer edge of the circular parts (30) of the outerhigh-energy element (26). The launcher (3) is therefore increased by theheight of the element (26). The case is crimped onto the front face (36)of the launcher (3).

In order to prevent the bare bullet (2) from freely leaving the launcher(3) at the start of firing under the uncrimping pressure p, a lockingmember (51) is placed in front of one of the circular parts (30) of theelement (26) and is jammed between the case and the circular slot (31)in the element (26). Since this locking member is longitudinally free,it is therefore released on the outside immediately on leaving thebarrel It may thus leave its housing and release the bare bullet (2).

EXAMPLE 4

The present invention may also apply to the firing of bullets in highlyrifled barrels, as the bullet represented in FIG. 8 shows.

The bare bullet (2) in accordance with the present invention isfin-stabilized. Only a very slight rotation over the trajectory isallowed due to the chamfers (20) made on the trailing edge of the fins(19). In order to preserve this mode of stabilization, it is necessaryto overcome the rotational velocity given by a highly rifled barrel.

FIG. 8 describes an illustrative embodiment corresponding to theseconditions. In this embodiment, the launcher (3) is divided into twoelements in a cross section: the front element (52) and the rear element(53).

The front element (52) is monobloc and axisymmetric. It no longer hascircular parts and external decompression slots. Its outside diameter(54) is slightly smaller than the inside diameter of the rifled barrel(55). An outside chamfer (56) is made at the front of this element inorder to allow proper insertion of the cartridge. The element (52) mayslide freely on the bare bullet (2).

The rear element (53) is also monobloc and axisymmetric. Its outsidediameter (h) is very slightly greater than the diameter (i) of thebottom of the rifling of the barrel (55). Its inside diameter (k) isgreater (by a few tenths of a millimeter) than the diameter (j) of thethrust plate (11). On its outside part, it also has a crimping slot (57)into which the collar of the metal case (60) fits by deformation.

A chamfer (58) is also made in order to permit proper engagement of therifling of the said element (53). A bush (59) having a low coefficientof friction is inserted between the two elements (52) and (53). Alocking member (61), interacting with the plate (11), provides the samefunction as that of the locking member (51) described in FIG. 7. Itstops the element (53) moving translationally but permits it completerotational freedom.

The operation of this device is as follows.

As soon as the pressure rises, uncrimping occurs and the bare bullet (2)and the element (52) cannot move forward because they aretranslationally locked in place by the locking member (51). The element(53) thus takes up the rifling of the barrel (55) and rotates at thespeed permitted by this rifling. During its movement, it forces the barebullet (2) and the element (52) into slight rotation just by friction.On leaving the barrel, the element (53) breaks under centrifugal action,leaving the possibility of the element (52) being released from the barebullet (2) by sliding.

I claim:
 1. A munition for a weapon of small, medium or large caliber,the munition including a cartridge comprising:a subprojectile includinga body and an axisymmetric element having a front central nozzlecommunicating with at least two annular nozzles, the axisymmetricelement forming a front part of the subprojectile and comprising ahollow outer element and a solid inner element, the inner element beingconnected to the body, the hollow outer element and the solid innerelement being connected together by at least two blades; a launcherinitially operatively engaged with the subprojectile and filling a boreof the weapon; a primed case surrounding the subprojectile and thelauncher; and a propellant charge within the primed case; wherein thelauncher detaches from the subprojectile upon leaving the weapon due toaerodynamic forces acting on the launcher; and wherein the front centralnozzle and the annular nozzles channel airflow through and around thesubprojectile.
 2. A munition as claimed in claim 1, wherein the solidinner element has an outside diameter less than or equal to an insidediameter of the hollow outer element, and the hollow outer element islocated in front of the solid inner element.
 3. A munition as claimed inclaim 1, wherein the solid inner element has an outside diameter greaterthan or equal to an inside diameter of the hollow outer element, and thehollow outer element is located in front of the solid inner element. 4.A munition as claimed in claim 1, wherein the subprojectile furthercomprises a conical head, and the hollow outer element has a front part,the conical head and the front part forming the central nozzlecommunicating with the annular nozzles.
 5. A munition as claimed inclaim 1, wherein the axisymmetric element has a front face having achamfer.
 6. A munition as claimed in claim 1, wherein the axisymmetricelement comprises a material having a lower impact strength than amaterial of the body of the subprojectile.
 7. A munition as claimed inclaim 1, wherein the launcher comprises a single monoblock element.
 8. Amunition as claimed in claim 1, wherein the launcher comprises aplurality of longitudinally contiguous elements.
 9. A munition asclaimed in claim 1, wherein the launcher comprises at least twomonoblock elements.
 10. A munition as claimed in claim 1, thesubprojectile further comprising a fin assembly operatively engaging arear end of the body; andwherein the launcher includes a rear facehaving a cutout corresponding to a shape of the fin assembly.
 11. Amunition as claimed in claim 10, wherein the body of the subprojectileincludes a head portion, and a thrust plate is located between the headportion and the fin assembly, the thrust plate abutting an annular seal.12. A munition as claimed in claim 10, wherein an annular lip extendsfrom the rear face of the launcher.